1. Field of the Invention
The present invention relates in general to a reverberation generation processor. In particular, the present invention relates to a reverberation generation processor for simulating a virtual environment.
2. Description of the Related Art
Virtual auditory displays (including computer games, virtual reality systems or computer music workstations) create virtual worlds in which a virtual listener can hear sounds generated from sound sources within these worlds. In addition to reproduce sound as generated by the source, the computer also processes the source signal to simulate the effects of the virtual environment on the sound emitted by the source. In a computer game, the player hears the sound that he/she would hear if he/she were located in the position of the virtual listener in the virtual world.
One important environmental factor is reverberation, which refers to the reflections of the generated sound which bounce off objects in the environment. Reverberation can be characterized by measurable criteria, such as the reverberation time, which is a measure of the time it takes for the reflections to become imperceptible.
FIG. 1 is a graph depicting the time and intensities of the direct sound, early reflection, and late reverberation components. The first signal that reaches the listener is the direct signal which undergoes no reflection. Subsequently, a series of discrete xe2x80x9cearlyxe2x80x9d reflections are received during an initial period of the reverberation response. Finally, after a critical time, the xe2x80x9clatexe2x80x9d reverberation is modeled statistically because of the combination and overlapping of the various reflections. The magnitudes of Reflections_delay and Reverb_delay are typically dependent on the size of the room and on the position of the source and the listener in the room.
Research continues in methods to create realistic sounds in virtual reality and gaming environments. However, the related circuits are complicated.
The object of the present invention is to provide a reverberation generation processor to simulate the reverberation effect as shown in FIG. 1.
To achieve the above-mentioned object, the present invention provides a reverberation generation processor for generating a specific auditory signal according to a predetermined virtual environment having characteristics of spatial dimension, sound reflection, and decline. The natural sequence generator generates a natural sequence having a predetermined number of items according to the characteristics of the virtual environment. The sequence adjusting device adjusts gains of the items and a time scale between the items of the natural sequence and outputs an audio signal. The filter processor filters a predetermined frequency band of the audio signal according to the characteristics of the virtual environment and divides the filtered audio signal into a high frequency audio signal and a low frequency audio signal. The high frequency reverberation generator transforms the high frequency audio signal to a high frequency reverberation signal. The low frequency reverberation generator transforms the low frequency audio signal to a low frequency reverberation signal. The output device combines the high frequency reverberation signal and the low frequency reverberation signal to output the specific auditory signal.